THE DISEASE TRIANGLE!

Fungicides are an important tool to protect crop health. However, a farmer cannot depend on fungicides alone to control crop disease. An integrated strategy using all cultural practices must be adopted to reduce disease levels. Reviewing the three factors that create the disease triangle will help, (Chapter 1). You need to consider:

  • what is the likelihood of the pathogen being present?
  • are the environmental factors conducive for disease development?
  • is the host crop susceptible to this pathogen and what agronomic practices have been used to enhance the crop?

Other Disease Management Practices and Considerations

  • variety and seed selection: choosing resistant cultivars and using seed with high vigour and zero or low levels of seed-borne diseases
  • sanitation: practice a diverse crop rotation to prevent specific pathogens from building up in the soil, remove infected residue and/or control volunteer crops which can serve as a reservoir for disease inoculum
  • good plant health: maintain competitive plants by using balanced fertility, plant the crop in the location it is best adapted to and use the proper seed rate, depth and date
  • don’t forget the importance of economics…a farmer is more likely to use pesticides if potential loss and his ability to recover investments are high. Commodity prices have a big influence on whether fungicides are used, i.e. malt barley, high value pulses and canola. It is also important to ‘sell’ the value of field scouting and good record keeping.

INTRODUCTION TO FUNGICIDES

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